Yes there are two locations at least in Patong. Returning the car to the airport at anytime is okay. They are open 24 hrs for returns, using the key-drop box if the office is closed.
Client
I gotta pick up the car at 0700 on 8/2 and return the car in the phuket airport by 2130 on 8/5
Agent
The office in Patong opens at 07:00 hrs. It is best to search using a tablet or PC/Computer as it will show you a map of Phuket and the available offices if you zoom in and navigate the map. Simply enter the search word ¨ Patong ¨